Papers by Keyword: Electron Beam Weld (EBW)

Abstract: High-frequency digital inverter power supply has the advantages of small, no noise, high efficiency, small ripp- le, and perfect protection, therefore, is gradually replacing the traditional electron beam welder which uses the 400Hz frequency generator. However, with more high frequency of the power supply, the design of the transformer used by the high-frequency high-voltage electron beam welding becomes difficult. Therefore, this paper put forward a diversified transformer mode and a voltage doubling rectifier circuit, which were used to reduce the transformer turns ratio, thus reducing the topology of the transformer distribution para- meters. Accordingly, a special high-frequency high-voltage electron beam welding tank is designed. Tests show that the set of performance indicators of the fuel tank meets the design goals to meet the actual needs of welding process.

Abstract: In the present work hot corrosion studies were carried out on electron beam welded AISI 304 and AISI 4140 dissimilar weldment in molten salt (K₂SO₄-60% NaCl) environment at 800 °C for 50 cycles. The weight gain follows parabolic law in all the cases. It is observed that the scale formation was maximum on 4140 side as compared on 304 side. Moreover higher content of Fe₂O₃ and Cr₂O₃ on scale over weld zone may be due to enrichment of this zone with Fe and Cr. This could be attributed to diffusion of chromium towards AISI 4140 from the AISI 304 and diffusion of iron from AISI 4140 side towards AISI 304. Furthermore weld interface suffered accelerated corrosion behavior in the chloride and sulfate mixed molten salt environment in the form of intense spalling and sputtering of its scale. The cracking of oxide scale on the weldment might be attributed to different composition of base metals, weld metal and oxide formed.

Abstract: Microstructures of electron beam welded joints for TA15 titanium alloy with different hydrogen contents were observed and analyzed by SEM and TEM. And the influence of hydrogen on microstructure of the joints was investigated. The results show that the microstructure of the weld metal is lamellar α+β phase after hydrogen charging. In the range of hydrogen contents discussed in this study (from 0 to 0.101 wt%), With the increase of hydrogen content, there is little change in the appearance of the microstructure of the weld metal. The presence of hydrogen can promote the growth of twins in electron beam welded joints. With the increase of hydrogen content, the number of twins is increased. When hydrogen content reaches to a certainty level, hydrides are found in TA15 electron beam welded joints.

Abstract: Fatigue test of AF1410 steel and two thickness of electron beam have been done, and fatigue properties of the base metal and EB-welded joints have been studied. The results showed that fatigue limit of electron beam welded joints was close to that of base metal under this test conditions, and the welded thickness has little effect on S-N curves of electron beam welded samples under this test conditions. From SEM fracture morphology, it can be seen that fracture morphology of the welded samples was not obvious different form base metal. In the instant-off area of electron beam welded sample, there was dimple-like morphology showing good ductility.

Abstract: Similar and dissimilar butt joint welds comprising combinations of commercially pure grade 4 titanium (CP-Ti), Ti-6Al-4V (Ti-64) and Ti-5Al-5V-5Mo-3Cr (Ti-5553) were created using the electron beam process. The resultant welds were studied by means of metallography, optical microscopy, mechanical testing and scanning electron microscopy. Mechanical testing was performed on welded samples to study the joint integrity and fracture characteristics. A scanning electron microscope investigation was performed on the fracture surface to reveal their fracture modes. While all weldments were crack free and most weldments exhibited mechanical properties comparable to the base metal, negligible ductility was exhibited during tensile testing joints of Ti-5553 welded to either Ti-64 or Ti-5553.

Abstract: Welding operation of aircraft engine sheet part will be analyzed in this paper. The sheet part is made of narrow Inconel 706 sheet pieces. During manufacturing process first sheets undergo the process of bending. Subsequently they are welded to produce the final shape. Finite element analysis will be used to model welding operation. The thermal field and its impact on the stress field will be analyzed. The produced results will be used to design the actual welding process. Sheets will be welded using electron beam welding, EBW, method. This method is characterized by high concentration of power which instantly melts metal. As a result small HAZ is produced and comparatively small distortions are introduced. EBW process is characterized mainly by three input parameters: beam voltage, beam current and welding speed. The goal of numerical simulation is to identify the values of input parameters that produce full-depth fusion zone. As a guideline for simulation the actual dependency between input parameters and weld pool geometry will be taken from calibration data for EB welding unit. Calibration was performed using 18-8 steel. Partial least square method will be used to project those data on Inconel 706 alloy.

Abstract: Four different weld shapes were obtained by choosing appropriate electron beam welding parameters, which are respectively named as bell shape, funnel shape, nail shape, and wedge shape. Fatigue examinations of the electron beam welded joints with different shapes were carried through. The influence of weld shape on fatigue performance of the joints was synthetically evaluated by analytic hierarchy mathematical model. The results show that weld shape effects fatigue property of the joint by electron beam welding. The sequencing of fatigue performance of the joints with four different shapes by analytic hierarchy process is bell shape, funnel shape, wedge shape, and nail shape. It is validated by practical trial results that the analytic hierarchy mathematical model is effective and practical.

Abstract: Electron beam welding process of AZ61 with 10mm thickness magnesium alloys was investigated. The influence of processing parameters including focusing current, welding beam current and welding speed was researched. The results show that an ideal weld bead can be formed by choosing processing parameters properly. Focusing current is main parameter that determines cross section shape. The beam current and welding speed are main parameters that determine the weld width and dimensions. The test results for typical welds indicate that the microhardness of the weld zone is better than that of the base meta1. A fine-grained weld region has been observed and no obvious heat-affected zone is found. The fusion zone mainly consists of small α-Mg phase and β-Mg17A112. The small grains and β phases in the joint are believed to play an important role in the increase of the strength of weld for AZ61 magnesium alloys.

Abstract: The fusion zone of an electron beam welded Ti-6Al-4V alloy presents a ' martensitic structure which leads to a change of mechanical properties. Starting from two manufacturing processing routes for the alloy (1) a  processing followed by the weld (the reference microstructure), (2) an  processing followed by welding and a post weld heat treatment (PWHT), the microstructure can be adjusted to avoid local difference of strength, fatigue properties and impact toughness. This results from the optimisation of the process and of the PWHT. The present work investigates the mechanical behaviour and the damage mechanism of both base metal and fusion zone in regards to the microstructure and to the heat treatment parameters.

Abstract: In this work, it was intended to improve the corrosion resistance of welds of A356 and AA6061 by adopting mainly a special welding techniques, viz., pulsed current gas tungsten arc welding (PCGTAW), electron beam welding (EBW) and friction stir welding (FSW). It was found that the corrosion resistance of A356 and AA6061 welds could be improved by PCGTAW technique rather than continuous current gas tungsten arc welding (CCGTAW). It can be further improved by using electron beam welding. Improved corrosion resistance in A356 welds could be obtained by selecting T6 temper rather than as cast condition. In the case of AA6061, improved corrosion resistance was achieved by selecting T4 temper rather than T6 temper. As for as the welding techniques, friction stir welding (FSW) is useful than fusion welding techniques like CCGTAW,PCGTAW and EBW for improving the corrosion resistance of both the welds.